The present invention relates to a process for manufacturing amorphous alloy powders, comprising the steps of: causing the molten metal which may be rendered amorphous to flow down from a nozzle of a crucible; and blowing a high-speed fluid from a spraying nozzle arranged below the nozzle of the crucible against the melt, thereby powderizing the melt.
Various processes for manufacturing an amorphous alloy in accordance with the shape (e.g., leaf-like shape, thin strip-like shape, thin wire-like shape, or powder) of an amorphous alloy to be manufactured are conventionally known.
The processes for manufacturing leaves of an amorphous alloy include the gun method, the piston-anvil method, the torsion-catapult method, and the like. The processes for continuous manufacturing a thin strip of an amorphous alloy include the centrifugal method, the melt-spinning method, and the double-roll method. The process for manufacturing thin wires include the water flow spinning method and the rotating fluid spinning method. The processes for manufacturing amorphous powders include the spray method, the cavitation method, the rotating spray method in fluid, and the atomizing method.
Amorphous alloys have different shapes in accordance with their intended application. Flakes, thin strips or wires of an amorphous alloy have predetermined shapes and are suitable for preparing predetermined parts, but are not suitable for parts having an arbitrary shape. In contrast to this, amorphous alloy powder yields, upon being pressed, elements, parts and the like of arbitrary complex shapes.
According to the principle of the atomizing method of manufacturing amorphous alloy powders, when molten metal is injected through a nozzle, a high-speed fluid jet (high-pressure gas, high-pressure steam, or high-speed water jet) is supplied to atomize the molten metal and to rapidly cool and solidify it. However, although the cooling rate of the conventional atomizing method is sufficient to allow preparation of fine amorphous powders, it is not sufficient to allow preparation of relatively coarse amorphous powders with satisfactory yield. For this reason, when amorphous alloy powders are prepared by the conventional atomizing method, a relatively large portion of the molten alloy is not formed into amorphous powders, resulting in a low manufacturing efficiency. Furthermore, on a single particle level, some particles are only partially rendered amorphous (only at the surface), resulting in a nonuniform degree of amorphousness. When such partially amorphous particles are used, the characteristics inherent in the amorphous alloy powder are deteriorated and a part having the desired characteristics cannot be prepared therefrom. Amorphous alloy powders obtained by the conventional method are of the spherical or teardrop particle shape. If such amorphous alloy powders are pressed without using a binder, the particles are unable to be pressed into a compact. Because of this simple particle shape almost no mechanical interaction among particles can be expected. Therefore, a binder is required to prepare an element or a part from amorphous alloy powders with spherical or teardrop particle shape. This imposes the problems of a high manufacturing cost, poor characteristics of a manufactured material or part, and complexity in the manufacturing process if the powder obtained by the conventional method is to be used for the manufacture of parts or the like on an industrial scale.